1. Field of the Invention
The present invention relates to an earphone used by being mounted on an auricle, and relates more particularly to an earphone equipped with an auricle-mounting member having elasticity.
2. Description of Related Art
As an earphone to be used by being mounted on the auricle, there has been used a one that is equipped with an auricle-mounting member formed by elastic foamed polyurethane or the like at a portion of the earphone that is inserted into the recess of the auricle through to the external acoustic meatus. The earphone equipped with the auricle-mounting member at a portion to be inserted into the auricle can be mounted on the ear by inserting the auricle-mounting member into the recess of the auricle through to the external acoustic meatus. Therefore, the earphone can be securely mounted on the auricle. Further, as the auricle-mounting member is made of an elastic material, the auricle-mounting member can be easily deformed elastically to match the shape of the recess of the auricle to the external acoustic meatus. Thus, it is also possible to obtain satisfactory feeling of the mounting.
As explained above, the earphone fitted with the auricle-mounting member having elasticity is mounted on the ear by inserting the auricle-mounting member into the recess of the auricle through to the external acoustic meatus. When the auricle-mounting member has been mounted on the ear, the auricle-mounting member is elastically deformed to seal the recess of the auricle to the external acoustic meatus. As a result, there is formed a sealed space in the area encircled by the drum membrane, a speaker unit accommodated in the earphone main body and the auricle-mounting member. This sealed space functions as an acoustic space, and changes the sound-pressure frequency characteristics of the sound emitted from the speaker unit. Particularly, this sealed space substantially increases the sensitivity of the low-pass frequency band, and generates a pool of indistinct sound, which lowers the distinctness of the sound.
Further, when the elastic auricle-mounting member has been inserted into the recess of the auricle through to the external acoustic meatus, there are variations in the feeling of the mounting depending on persons and also depending on how the earphone is mounted on the auricle. There also arises a variation in the level of sealing. When even a slight variation has occurred in the sealing level, the sound-pressure frequency characteristics vary substantially. As a result, the sound quality varies depending on the user of the earphone.
In order to obtain a constant sound-pressure frequency regardless of the users of the earphone without an influence of the variation in the mounting state, there has been proposed a modified earphone. According to this earphone, small holes are made on a part of the housing that constitutes the main body of the earphone. When the earphone has been mounted on the ear, these small holes mitigate the sealing level of the space encircled by the drum membrane, a speaker unit accommodated in the earphone main body and the auricle-mounting member.
However, when only these small holes are made on a part of the housing, a resonance is generated in the intermediate-pass to high-pass frequency bands depending on the sizes of the small holes. As a result, a peak of sound pressure is generated in the intermediate-pass to high-pass frequency bands, and this deteriorates the sound-pressure frequency characteristics.
It is, therefore, an object of the present invention to provide an earphone which provides a user with a satisfactory feeling of the wearing of the earphone when mounted on the auricle regardless of who uses this earphone, which can usually provide reproduced acoustics in satisfactory sound quality, and which does not change the listening sound quality regardless of users of the earphone.
In order to achieve the above object by solving the conventional problems, according to a first aspect of the present invention, there is provided an earphone comprising: a speaker unit; a housing that accommodates the speaker unit and that is formed with an opening for discharging sound from the front side of the speaker unit; and an elastic auricle-mounting member disposed surrounding the opening, wherein a space formed by the drum membrane, the speaker unit and the auricle-mounting member at the time of mounting the earphone on the auricle is communicated to the outside of the earphone via a ventilation resistor. Therefore, it is possible to prevent deterioration in the sound quality due to the pooled indistinct sound that is generated by sealing the space encircled by the drum membrane, the speaker unit and the auricle-mounting member.
As the space encircled by the drum membrane, the speaker unit and the auricle-mounting member is communicated to the outside of the earphone via the ventilation resistor, the generation of a resonance in the intermediate-pass to high-pass frequency bands can be restricted. As a result, it is possible to obtain flat sound-pressure frequency characteristics over the low-pass to high-pass bands as improved sound-pressure frequency characteristics.
Further, according to a second aspect of the invention, there is provided an earphone wherein the space formed by the drum membrane, the speaker unit and the auricle-mounting member at the time of mounting the earphone on the auricle is communicated to the outside of the earphone via ventilation holes made on the housing via the ventilation resistor.
Further, according to a third aspect of the invention, there is provided an earphone comprising: a speaker unit; a housing that accommodates the speaker unit and that is formed with an opening for discharging sound from the front side of the speaker unit; and an elastic auricle-mounting member disposed surrounding the opening, wherein a space formed by the drum membrane, the speaker unit and the auricle-mounting member at the time of mounting the earphone on the auricle is communicated to a space formed by a rear surface of the speaker unit and the housing via a ventilation resistor. Therefore, it is possible to prevent deterioration in the sound quality due to the pooled indistinct sound that is generated by the sealing of the space encircled by the drum membrane, the speaker unit and the auricle-mounting member.